phrase = "Don't panic!"
plist = list(phrase)
print(phrase) #打印字符串
print(plist) # 列表格式
for i in range(4):
    plist.pop()
    # 循环删除列表最后一位四次
print(plist)
plist.pop(0)
plist.pop(2)
plist.extend([plist.pop(),plist.pop()])
plist.insert(2,plist.pop(3))
new_phrase =''.join(plist)
print(plist)
print(new_phrase)


'''
Don't panic!
['D', 'o', 'n', "'", 't', ' ', 'p', 'a', 'n', 'i', 'c', '!']
['D', 'o', 'n', "'", 't', ' ', 'p', 'a']
['o', 'n', ' ', 't', 'a', 'p']
on tap
'''